[antlr-interest] Examining characters in lexer
Johannes Luber
jaluber at gmx.de
Thu Mar 12 14:00:19 PDT 2009
Dennis Brothers schrieb:
> Is there a special symbol or method that returns the character about
> to be scanned? In order to handle a variety of (natural) languages,
> I'd like to use Unicode categories to detect various character types
> (particularly letters).
>
> I want to do something like
>
> fragment LETTER : { Char.IsLetter( $char ) } ?=> . ;
>
> where $char is the next character to be scanned and Char.IsLetter() is
> a .NET method that examines a character's Unicode category and returns
> true if it's one of the letter categories.
>
> While I'm at it, is it legal to use a gated predicate like the above
> in a lexer?
>
> Thanks -
> - Dennis Brothers
Try LA(1) or input.LA(1).
Johannes
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